The present invention relates to a current detection device for detecting electric current flowing through a conductor, for example, in a branch connection box in a vehicle.
FIGS. 7 and 8 show a conventional current detection device of the type described. As shown in these Figures, the current detection device includes a main housing 1 of a rectangular configuration, and a tubular portion 2, formed on the bottom of the housing 1, that extends in an upward-downward direction, the tubular portion 2 having a bore 3 of a rectangular cross-section extending through the housing 1. A penetration conductor 4, comprising a bus bar through which current to be measured flows, is passed upwardly through the bore 3, with an upper end portion thereof projecting upwardly beyond the main housing 1.
One end portion of a conductor 5 comprising a bus bar is mated with the upper end portion of the penetration conductor 4 which projects upwardly beyond the main housing 1, and is fastened thereto by a bolt 8 (which has a special head) and a nut 9 through washers 6 and 7.
A magnetic core 10 having a C-shape is mounted on the outer periphery of the tubular portion 2 within the main housing 1, and a magneto-electric conversion element 11 comprising a Hall element is provided in a gap 10A in the magnetic core 10. This magneto-electric conversion element 11 extends upright from a circuit board 12 within the main housing 1. An amplifier circuit 13 and so on are mounted on the circuit board 12, and a connector 14 for taking out a detection output and for feeding power to the amplifier circuit 13 is also provided. Although not shown in the drawings, there is provided printed wiring for providing a path from the magneto-electric element 11 to the connector 14 via the amplifier circuit 13. A provisional retainer 15 is used for provisionally retaining the magnetic core 10.
The magnetic core 10, the magneto-electric conversion element 11, the circuit board 12, the amplifier circuit 13, the connector 14, the provisional retainer 15, etc. jointly constitute a non-contact current detection unit 16.
In such a conventional current detection device, however, the special bolt 8, used for connecting the penetration conductor 4 has seven radial grooves 8A formed in its head the other conductor 5, and therefore, a problem has arisen in that the fastening operation can not be effected without a special driver. Another problem is that time and labor are required for the fastening operation since either the bolt 8 or the nut 9 need to be rotated a plurality of times.
A further problem is that time and labor are required for creating a hole 4A through the penetration conductor 4 for passing the bolt 8 through this hole.